package com.wang.springframework.beans.factory.support;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import com.wang.springframework.beans.BeansException;
import com.wang.springframework.beans.PropertyValue;
import com.wang.springframework.beans.PropertyValues;
import com.wang.springframework.beans.factory.*;
import com.wang.springframework.beans.factory.config.*;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

/**
 * @author wangjianhua
 * @Description
 * @date 2021/8/25/025 14:32
 **/
public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFactory implements AutowireCapableBeanFactory {

    private InstantiationStrategy instantiationStrategy = new SimpleInstantiationStrategy();

    @Override
    protected Object createBean(String beanName, BeanDefinition beanDefinition, Object[] args) throws BeansException {
        //判断是否返回代理对象
        Object bean = resolveBeforeInstantiation(beanName, beanDefinition);
        if(null != bean){
            return bean;
        }

        return  doCreateBean(beanName, beanDefinition, args);
    }

    protected Object doCreateBean(String beanName,BeanDefinition beanDefinition,Object[] args) throws BeansException{
        Object bean = null;
        try
         {
            //实例化bean
             bean = createBeanInstance(beanDefinition, beanName, args);

             //处理循环依赖,将实例化后的Bean对象提前放入缓存中暴露出来
             if(beanDefinition.isSingleton()){
                Object finalBean = bean;
                addSingletonFactory(beanName,() -> getEarlyBeanReference(beanName,beanDefinition,finalBean));
             }

             //实例化后判断
             boolean continueWithPropertyPopulation = applyBeanPostProcessorsAfterInstantiation(beanName,bean);
             if(!continueWithPropertyPopulation){
                return bean;
             }
             //在设置bean属性之前 允许BeanPostProcessor修改属性值
             applyBeanPostProcessorBeforeApplyingPropertyValues(beanName,bean,beanDefinition);
             //给bean填充属性
             applyPropertyValues(beanName,bean,beanDefinition);
             //执行bean的初始化方法和 BeanPostProcessor的前置和后置处理方法
             bean = initializeBean(beanName,bean,beanDefinition);
         }
        catch (Exception e)
        {
            throw new BeansException("Instantiation of bean failed",e);
        }

        //注册实现了DisposableBean接口的bean对象
        registerDisposableBeanIfNecessary(beanName,bean,beanDefinition);

        //判断scope
        Object exposedObject = bean;
        if(beanDefinition.isSingleton()){
            //获取代理对象
            exposedObject = getSingleton(beanName);
            registerSingleton(beanName,exposedObject);
        }

        return exposedObject;

    }

    protected Object getEarlyBeanReference(String beanName,BeanDefinition beanDefinition,Object bean){
        Object exposedObject = bean;
        for (BeanPostProcessor beanPostProcessor : getBeanPostProcessors()) {
            if(beanPostProcessor instanceof InstantiationAwareBeanPostProcessor){
                exposedObject = ((InstantiationAwareBeanPostProcessor) beanPostProcessor).getEarlyBeanReference(exposedObject, beanName);
                if(null == exposedObject){
                    return exposedObject;
                }
            }
        }
        return exposedObject;
    }


    /**
     * Bean实例化后对于返回为false的对象 不再执行后续设置bean对象属性的操作
     * @param beanName beanName
     * @param bean bean
     * @return boolean
     */
    private boolean applyBeanPostProcessorsAfterInstantiation(String beanName,Object bean){
        boolean continueWithPropertyPopulation = true;
        for (BeanPostProcessor beanPostProcessor : getBeanPostProcessors()) {
            if(beanPostProcessor instanceof  InstantiationAwareBeanPostProcessor){
                InstantiationAwareBeanPostProcessor instantiationAwareBeanPostProcessor = (InstantiationAwareBeanPostProcessor) beanPostProcessor;
                if(!instantiationAwareBeanPostProcessor.postProcessAfterInstantiation(bean, beanName)){
                    continueWithPropertyPopulation = false;
                    break;
                }
            }
        }
        return continueWithPropertyPopulation;
    }

    /**
     * 在设置bean属性之前 允许 BeanPostProcessor修改属性值
     * @param beanName beanName
     * @param bean bean
     * @param beanDefinition beanDefinition
     */
    protected void applyBeanPostProcessorBeforeApplyingPropertyValues(String beanName,Object bean,BeanDefinition beanDefinition){
        for (BeanPostProcessor beanPostProcessor : getBeanPostProcessors()) {
            if(beanPostProcessor instanceof InstantiationAwareBeanPostProcessor){
                PropertyValues pvs = ((InstantiationAwareBeanPostProcessor) beanPostProcessor).postProcessPropertyValues(beanDefinition.getPropertyValues(),bean,beanName);
                if(null != pvs){
                    for (PropertyValue propertyValue : pvs.getPropertyValues()) {
                        beanDefinition.getPropertyValues().addPropertyValue(propertyValue);
                    }
                }
            }
        }
    }

    protected Object resolveBeforeInstantiation(String beanName,BeanDefinition beanDefinition){
        Object bean = applyBeanPostProcessorsBeforeInstantiation(beanDefinition.getBeanClass(), beanName);
        if(null != bean){
            bean = applyBeanPostProcessorsAfterInitialization(bean,beanName);
        }
        return bean;
    }

    protected Object applyBeanPostProcessorsBeforeInstantiation(Class<?> beanClass,String beanName){
        for (BeanPostProcessor beanPostProcessor : getBeanPostProcessors()) {
            if(beanPostProcessor instanceof InstantiationAwareBeanPostProcessor){
                Object result = ((InstantiationAwareBeanPostProcessor) beanPostProcessor).postProcessBeforeInstantiation(beanClass, beanName);
                if(null != result){
                    return result;
                }
            }
        }
        return null;
    }

    protected void registerDisposableBeanIfNecessary(String beanName,Object bean,BeanDefinition beanDefinition){
        //非singleton的bean不执行销毁方法
        if(!beanDefinition.isSingleton()){
            return;
        }
        if(bean instanceof DisposableBean || StrUtil.isNotEmpty(beanDefinition.getDestroyMethodName())){
            registerDisposableBean(beanName,new DisposableBeanAdapter(bean, beanName, beanDefinition));
        }
    }

    protected Object createBeanInstance(BeanDefinition beanDefinition,String beanName,Object[] args){
        Constructor<?> constructorToUse = null;
        Class<?> beanClass = beanDefinition.getBeanClass();
        Constructor<?>[] declaredConstructors = beanClass.getDeclaredConstructors();
        for (Constructor<?> ctor : declaredConstructors) {
            if(null != args && ctor.getParameterTypes().length == args.length){
                constructorToUse = ctor;
                break;
            }
        }
        return getInstantiationStrategy().instantiate(beanDefinition,beanName,constructorToUse,args);
    }

    /**
     * bean属性填充
     */
    protected void applyPropertyValues(String beanName,Object bean,BeanDefinition beanDefinition){
        try
        {
            PropertyValues propertyValues = beanDefinition.getPropertyValues();
            for (PropertyValue propertyValue : propertyValues.getPropertyValues()) {

                String name = propertyValue.getName();
                Object value = propertyValue.getValue();

                if(value instanceof BeanReference){
                    BeanReference beanReference = (BeanReference) value;
                    value = getBean(beanReference.getBeanName());
                }

                BeanUtil.setFieldValue(bean,name,value);
            }
        }
        catch (Exception e)
        {
            throw new BeansException("Error setting property values:"+beanName);
        }
    }

    public InstantiationStrategy getInstantiationStrategy() {
        return instantiationStrategy;
    }

    public void setInstantiationStrategy(InstantiationStrategy instantiationStrategy) {
        this.instantiationStrategy = instantiationStrategy;
    }


    /**
     * 初始化bean
     * @param beanName beanName
     * @param bean bean
     * @param beanDefinition beanDefinition
     * @return bean
     */
    private Object initializeBean(String beanName,Object bean,BeanDefinition beanDefinition){

        if(bean instanceof Aware){
            if(bean instanceof BeanFactoryAware){
                ((BeanFactoryAware) bean).setBeanFactory(this);
            }
            if(bean instanceof BeanClassLoaderAware){
                ((BeanClassLoaderAware) bean).setBeanClassLoader(getBeanClassLoader());
            }
            if(bean instanceof BeanNameAware){
                ((BeanNameAware) bean).setBeanName(beanName);
            }
        }

        //1. 执行 BeanPostProcessor Before处理

        Object wrappedBean = applyBeanPostProcessorsBeforeInitialization(bean, beanName);

        //  执行bean对象的初始化方法
        try
        {
            invokeInitMethods(beanName, wrappedBean, beanDefinition);
        }
        catch (Exception e)
        {
            throw new BeansException("Invocation of init method of bean["+beanName+"] failed",e);
        }


        //2. 执行 BeanPostProcessor After处理
        wrappedBean = applyBeanPostProcessorsAfterInitialization(bean,beanName);
        return wrappedBean;
    }

    private void invokeInitMethods(String beanName,Object bean,BeanDefinition beanDefinition) throws Exception{
        //1.实现接口 InitializingBean
        if(bean instanceof InitializingBean){
            ((InitializingBean) bean).afterPropertiesSet();
        }

        //2. 注解配置 init-method 判断是为了避免二次执行销毁
        String initMethodName = beanDefinition.getInitMethodName();
        if(StrUtil.isNotEmpty(initMethodName)){
            Method initMethod = beanDefinition.getBeanClass().getMethod(initMethodName);
            if(null==initMethod){
                throw new BeansException("Could not find an init method named '"+initMethodName+"' on bean with name '"+beanName+"'");
            }
            initMethod.invoke(bean);
        }
    }

    @Override
    public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName) throws BeansException {
        Object result = existingBean;
        for (BeanPostProcessor processor : getBeanPostProcessors()) {
            Object current = processor.postProcessBeforeInitialization(result, beanName);
            if(null == current){
                return result;
            }
            result = current;
        }
        return result;
    }

    @Override
    public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) throws BeansException {
        Object result = existingBean;
        for (BeanPostProcessor processor : getBeanPostProcessors()) {
            Object current = processor.postProcessAfterInitialization(result, beanName);
            if(null == current){
                return result;
            }
            result = current;
        }
        return result;
    }
}
